Urea-containing silanes, process for preparation thereof and use thereof

ABSTRACT

The invention relates to urea-containing silanes of the formula I 
     
       
         
         
             
             
         
       
     
     which are prepared by reacting urea-containing disulphide silanes of the formula II 
     
       
         
         
             
             
         
       
     
     with sulphur or
 
in a first step, reacting an aminosilane of the formula III
 
     
       
         
         
             
             
         
       
     
     with an isocyanate of the formula IV 
     
       
         
         
             
             
         
       
     
     and, in a second step, reacting the product from the first process step with sodium polysulphide of the formula (V) 
       Na 2 S x   (V)
 
     or
 
in a first step, reacting an isocyanatosilane of the formula VII
 
     
       
         
         
             
             
         
       
     
     with an amine of the formula VIII 
     
       
         
         
             
             
         
       
     
     and, in a second step, reacting the product from the first process step with sodium polysulphide of the formula (V) 
       Na 2 S x   (V).

The invention relates to urea-containing silanes, to processes for preparation thereof and to the use thereof.

CAS 1184961-62-3, 442527-46-0 and 498553-03-0 disclose compounds of the formula

In addition, US 20030191270 A1 discloses silanes of the formula

JP 2002201312 A discloses rubber modifiers of the formula

In addition, J. Mat. Chem. 2009, 19, 4746-4752 discloses gold nanoparticles within SH-functionalized framework structures formed from mesoporous silicas and the preparation of urea-containing silanes. In the known process, organic solvents are used.

Disadvantages of the known urea-containing disulphide silanes are poor reinforcement characteristics and high rolling resistance.

It is an object of the present invention to provide urea-containing silanes having improved reinforcement characteristics and rolling resistance in rubber mixtures compared to urea-containing silanes known from the prior art.

The invention provides a urea-containing silane of the formula I

where R¹ are the same or different and are C1-C10 alkoxy groups, preferably methoxy or ethoxy group, C2-C10 cyclic dialkoxy groups, phenoxy group, C4-C10 cycloalkoxy groups, C6-C20 aryl groups, preferably phenyl, C1-C10 alkyl groups, preferably methyl or ethyl, C2-C20 alkenyl group, C7-C20 aralkyl group or halogen, preferably Cl, and R are the same or different and are a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30, preferably C1-C20, more preferably C1-C10, even more preferably C1-C7, especially preferably C2 and C3, hydrocarbon group optionally substituted by F—, Cl—, Br—, I—, —CN or HS—, and x is an integer from 3 to 8, preferably 3 or 4.

Urea-containing silanes may be mixtures of urea-containing silanes of the formula I.

The process product may comprise oligomers which form through hydrolysis and condensation of the alkoxysilane functions of the urea-containing silanes of the formula I.

The urea-containing silanes of the formula I may be applied to a support, for example wax, polymer or carbon black. The urea-containing silanes of the formula I may be applied to a silica, in which case the binding may be physical or chemical.

R may preferably be

-   -   —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂—, —CH(CH₃)—,         —CH₂CH(CH₃)—, —CH(CH₃)CH₂—, —C(CH₃)₂—, —CH(C₂H₅)—,         —CH₂CH₂CH(CH₃)—, —CH(CH₃)CH₂CH₂—,     -   —CH₂CH(CH₃)CH₂—, —CH₂CH₂CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂CH₂CH₂—,     -   —CH₂CH₂CH₂CH₂CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—,     -   —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—,         —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—,         —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—,         —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—,         —CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂CH₂—         -   or

R¹ may preferably be methoxy or ethoxy.

Urea-containing silanes of the formula I may preferably be:

-   -   ((EtO)₃Si—CH₂—NH—CO—NH—CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂,     -   ((EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂—NH—CO—NH—CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂,     -   ((MeO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂ or     -   ((MeO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂.

An especially preferred compound is of the formula

-   -   (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃.

The invention further provides a first process for preparing the inventive urea-containing silanes of the formula I

where R¹, R and x are each as defined above, which is characterized in that a urea-containing disulphide silane of the formula II

is reacted with sulphur.

The reaction can be conducted with exclusion of air.

The reaction may be carried out under a protective gas atmosphere, for example under argon or nitrogen, preferably under nitrogen.

The first process according to the invention can be conducted at standard pressure, elevated pressure or reduced pressure. Preferably, the process according to the invention can be conducted at standard pressure.

Elevated pressure may be a pressure of 1.1 bar to 100 bar, preferably of 1.5 bar to 50 bar, more preferably of 2 bar to 20 bar and very preferably of 2 to 10 bar.

Reduced pressure may be a pressure of 1 mbar to 1000 mbar, preferably 1 mbar to 500 mbar, more preferably 1 mbar to 250 mbar, very preferably 5 mbar to 100 mbar.

The first process according to the invention can be conducted between 30° C. and 180° C., preferably between 80° C. and 165° C., more preferably between 120° C. and 160° C.

The reaction can be effected in a solvent, for example methanol, ethanol, propanol, butanol, cyclohexanol, N,N-dimethylformamide, dimethyl sulphoxide, pentane, hexane, cyclohexane, heptane, octane, decane, toluene, xylene, acetone, acetonitrile, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloromethane, tetrachloroethylene, diethyl ether, methyl tert-butyl ether, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine or methyl acetate. The reaction can preferably be effected without solvent.

The reaction can be conducted without organic solvent. The solvent may be water.

The urea-containing silane of the formula I obtainable by the first process according to the invention can be obtained in a yield of greater than 50%, preferably greater than 60%, very preferably greater than 70%.

The invention further provides a second process for preparing the inventive urea-containing silanes of the formula I

where R¹, R and x are each as defined above, which is characterized in that, in a first step, an aminosilane of the formula III

is reacted with an isocyanate of the formula IV

where R and R¹ are each as defined above and Hal is F, Cl, Br or I, preferably CI, and, in a second step, the product from the first process step is reacted with sodium polysulphide of the formula (V)

Na₂S_(x)  (V)

where x is as defined above.

Aminosilanes of the formula III may preferably be:

-   -   (C₂H₅O)₃Si—CH₂—NH₂,     -   (C₂H₅O)₃Si—CH₂CH₂—NH₂,     -   (C2H₅O)₃Si—CH₂CH₂CH₂—NH₂,     -   (CH₃O)₃Si—CH₂—NH₂,     -   (CH₃O)₃Si—CH₂CH₂—NH₂ or     -   (CH₃O)₃Si—CH₂CH₂CH₂—NH₂.

Isocyanates of the formula IV may preferably be:

-   -   OCN—CH₂—Cl,     -   OCN—CH₂CH₂—Cl or     -   OCN—CH₂CH₂CH₂—Cl.

In the second process according to the invention, the first and second process step can be effected in one reaction vessel by addition of all the reactants.

In the first step of the second process according to the invention, aminosilane of the formula III can be metered into isocyanate of the formula IV.

In the first step of the second process according to the invention, the isocyanate of the formula IV can preferably be metered into aminosilane of the formula III.

In the first step of the second process according to the invention, the aminosilane of the formula III can be used relative to the isocyanate of the formula IV in a molar ratio of 0.85:1 to 1.15:1, preferably 0.90:1 to 1.10:1, more preferably in a ratio of 0.95:1 to 1.05:1.

The reaction in the first step of the second process according to the invention can be conducted with exclusion of air.

The reaction in the first step of the second process according to the invention can be conducted under a protective gas atmosphere, for example under argon or nitrogen, preferably under nitrogen.

The first step of the second process according to the invention can be conducted at standard pressure, elevated pressure or reduced pressure. Preferably, the process according to the invention can be conducted at standard pressure.

Elevated pressure may be a pressure from 1.1 bar to 100 bar, preferably of 1.5 bar to 50 bar, more preferably of 2 bar to 20 bar and very preferably of 2 to 10 bar.

Reduced pressure may be a pressure of 1 mbar to 1000 mbar, preferably 1 mbar to 500 mbar, more preferably 1 mbar to 250 mbar, very preferably 5 mbar to 100 mbar.

The first step of the second process according to the invention can be conducted between −78° C. and 100° C., preferably between −70° C. and 50° C., more preferably between −65° C. and 25° C.

The reaction in the first step of the second process according to the invention can be effected without solvent or in a solvent, for example methanol, ethanol, propanol, butanol, cyclohexanol, N,N-dimethylformamide, dimethyl sulphoxide, pentane, hexane, cyclohexane, heptane, octane, decane, toluene, xylene, acetone, acetonitrile, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloromethane, tetrachloroethylene, diethyl ether, methyl tert-butyl ether, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine or ethyl acetate. The solvent may preferably be dichloromethane, ethanol, methyl tert-butyl ether, toluene, ethyl acetate, pentane or hexane.

The reaction in the first step of the second process according to the invention can be conducted without organic solvent. The solvent may be water.

The solvent in the first step of the second process according to the invention can subsequently be removed, preferably distilled off.

The reaction product from the first step of the second process according to the invention can subsequently be filtered and washed with an organic solvent. Preferably, an alkane can be used for washing, more preferably hexane.

The reaction product from the first step of the second process according to the invention can be dried after filtration. The drying can be effected at temperatures of 20° C.-100° C., preferably of 25° C.-50° C. The drying can be effected at a reduced pressure of 1-500 mbar.

The urea-containing halosilane of the formula VI, obtainable in the first step of the second process according to the invention,

can be obtained in a yield of greater than 50%, preferably greater than 60%, very preferably greater than 70%.

The reaction in the second step of the second process according to the invention can be conducted with exclusion of air.

The reaction in the second step of the second process according to the invention can be conducted under a protective gas atmosphere, for example under argon or nitrogen, preferably under nitrogen.

The second step of the second process according to the invention can be conducted at standard pressure, elevated pressure or reduced pressure. Preferably, the process according to the invention can be conducted at standard pressure.

Elevated pressure may be a pressure from 1.1 bar to 100 bar, preferably of 1.5 bar to 50 bar, more preferably of 2 bar to 20 bar and very preferably of 2 to 10 bar.

Reduced pressure may be a pressure of 1 mbar to 1000 mbar, preferably 1 mbar to 500 mbar, more preferably 1 mbar to 250 mbar, very preferably 5 mbar to 100 mbar.

The second step of the second process according to the invention can be conducted between 20° C. and 150° C., preferably between 40° C. and 100° C., more preferably between 45° C. and 80° C.

The reaction in the second step of the second process according to the invention can be effected without solvent or in a solvent, for example methanol, ethanol, propanol, butanol, cyclohexanol, N,N-dimethylformamide, dimethyl sulphoxide, pentane, hexane, cyclohexane, heptane, octane, decane, toluene, xylene, acetone, acetonitrile, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloromethane, tetrachloroethylene, diethyl ether, methyl tert-butyl ether, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine or ethyl acetate. The solvent may preferably be ethanol.

The reaction in the second step of the second process according to the invention can be conducted without organic solvent. The solvent may be water.

The reaction product in the second step of the second process according to the invention can be filtered, and the filtercake can be washed with an organic solvent. Preferably, an alcohol can be used for washing, more preferably ethanol, or an alkane, more preferably hexane.

The solvent in the second step of the second process according to the invention can subsequently be removed, preferably distilled off.

The reaction product in the second step of the second process according to the invention can be dried after filtration and removal of solvent. The drying can be effected at temperatures of 20° C.-100° C., preferably of 25° C.-50° C. The drying can be effected at a reduced pressure of 1-500 mbar.

The urea-containing silane of the formula I, obtainable in the second step of the second process according to the invention,

can be obtained in a yield of greater than 50%, preferably greater than 60%, very preferably greater than 70%.

In a preferred embodiment of the second process according to the invention, the isocyanate of the formula IV can be metered at −78 to −50° C. into the aminosilane of the formula III in ethanol, then the reaction mixture can be heated to 50° C., sodium polysulphide of the formula V can be added in portions, then the mixture can be refluxed, preferably at 78° C., cooled after the reaction has ended and filtered, and the ethanol solvent can be removed under reduced pressure.

The product prepared by the second process according to the invention may have a residual content of urea-containing halosilane of the formula VI of less than 25 mol %, preferably less than 10 mol %, more preferably less than 5 mol %, very preferably less than 3 mol %.

The relative molar percentages of the urea-containing halosilanes of the formula VI in the product prepared by the second process according to the invention are determined in the ¹H NMR by integration of the hydrogen atoms in the —CH₂CH ₂—Cl group of the compounds of the formula VI against the hydrogen atoms in the Si—CH ₂— group of the urea-containing silane of the formula I.

For the substance of the formula VI (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—Cl, for example, the integral of the hydrogen atoms of the —CH₂CH ₂—Cl group (δ=3.17 ppm) is used for the determination of the relative contents.

The product prepared by the second process according to the invention may have a residual content of aminosilane of the formula III of less than 10 mol %, preferably less than 5 mol %, more preferably less than 1 mol %, very preferably less than 0.1 mol %.

The relative molar percentages of the aminosilanes of the formula III in the product prepared by the second process according to the invention are determined in the ¹³C NMR by integration of the carbon atoms in the —CH₂—NH₂ group of the aminosilanes of the formula III against the carbon atoms in the Si—CH₂— group of the urea-containing silane of the formula I.

For the substance of the formula III (EtO)₃Si—CH₂—CH₂—CH₂—NH₂, for example, the integral of the carbon atoms of the —CH₂—NH₂ group (δ=45.15 ppm) is used for the determination of the relative contents.

The product prepared by the second process according to the invention may have a residual content of isocyanate of the formula IV of less than 25 mol %, preferably less than 10 mol %, more preferably less than 5 mol %, very preferably less than 3 mol %.

The relative molar percentages of the isocyanates of the formula IV in the product prepared by the second process according to the invention are determined in the ¹³C NMR by integration of the carbon atoms in the OCN—CH₂— group of the isocyanates of the formula IV against the carbon atoms in the Si—CH₂— group of the urea-containing silane of the formula I.

For the substance of the formula IV OCN—CH₂—CH₂—Cl, for example, the integral of the carbon atoms of the OCN—CH₂— group (δ=124.33 ppm) is used for the determination of the relative contents.

The invention further provides a third process for preparing the inventive urea-containing silanes of the formula I

where R¹, R and x are each as defined above, which is characterized in that, in a first step, an isocyanatosilane of the formula VII

is reacted with an amine of the formula VIII

where R and R¹ are each as defined above and Hal is F, Cl, Br or I, preferably CI, and, in a second step, the product from the first process step is reacted with sodium polysulphide of the formula (V)

Na₂S_(x)  (V)

where x is as defined above.

Isocyanatosilanes of the formula VII may preferably be:

-   -   (C₂H₅O)₃Si—CH₂—NCO,     -   (C₂H₅O)₃Si—CH₂CH₂—NCO,     -   (C₂H₅O)₃Si—CH₂CH₂CH₂—NCO,     -   (CH₃O)₃Si—CH₂—NCO,     -   (CH₃O)₃Si—CH₂CH₂—NCO or     -   (CH₃O)₃Si—CH₂CH₂CH₂—NCO.

Amines of the formula VIII may preferably be:

-   -   H₂N—CH₂—Cl,     -   H₂N—CH₂CH₂—Cl or     -   H₂N—CH₂CH₂CH₂—Cl.

In the third process according to the invention, the first and second process step can be effected in one reaction vessel by addition of all the reactants.

In the first step of the third process according to the invention, amine of the formula VIII can be metered into isocyanatosilane of the formula VII.

In the first step of the third process according to the invention, the isocyanatosilane of the formula VII can preferably be metered into amines of the formula VIII.

In the first step of the third process according to the invention, the isocyanatosilane of the formula VII can be used relative to amine of the formula VIII in a molar ratio of 0.85:1 to 1.15:1, preferably 0.90:1 to 1.10:1, more preferably in a ratio of 0.95:1 to 1.05:1.

The reaction in the first step of the third process according to the invention can be conducted with exclusion of air.

The reaction in the first step of the third process according to the invention can be conducted under a protective gas atmosphere, for example under argon or nitrogen, preferably under nitrogen.

The first step of the third process according to the invention can be conducted at standard pressure, elevated pressure or reduced pressure. Preferably, the process according to the invention can be conducted at standard pressure.

Elevated pressure may be a pressure from 1.1 bar to 100 bar, preferably of 1.5 bar to 50 bar, more preferably of 2 bar to 20 bar and very preferably of 2 to 10 bar.

Reduced pressure may be a pressure of 1 mbar to 1000 mbar, preferably 1 mbar to 500 mbar, more preferably 1 mbar to 250 mbar, very preferably 5 mbar to 100 mbar.

The first step of the third process according to the invention can be conducted between −78° C. and 100° C., preferably between −75° C. and 60° C., more preferably between −70° C. and 40° C.

The reaction in the first step of the third process according to the invention can be effected without solvent or in a solvent, for example methanol, ethanol, propanol, butanol, cyclohexanol, N,N-dimethylformamide, dimethyl sulphoxide, pentane, hexane, cyclohexane, heptane, octane, decane, toluene, xylene, acetone, acetonitrile, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloromethane, tetrachloroethylene, diethyl ether, methyl tert-butyl ether, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine or ethyl acetate.

The reaction in the first step of the third process according to the invention can be conducted without organic solvent. The solvent may preferably be ethanol.

The solvent in the first step of the third process according to the invention can subsequently be removed, preferably distilled off.

The reaction product in the first step of the third process according to the invention can subsequently be filtered and washed with an organic solvent. Preferably, an alkane can be used for washing, more preferably hexane.

The reaction product in the first step of the third process according to the invention can be dried after filtration. The drying can be effected at temperatures of 20° C.-100° C., preferably of 25° C.-50° C. The drying can be effected at a reduced pressure of 1-500 mbar.

The urea-containing halosilane of the formula VI, obtainable in the first step of the third process according to the invention,

can be obtained in a yield of greater than 50%, preferably greater than 60%, very preferably greater than 70%.

The reaction in the second step of the third process according to the invention can be conducted with exclusion of air.

The reaction in the second step of the third process according to the invention can be conducted under a protective gas atmosphere, for example under argon or nitrogen, preferably under nitrogen.

The second step of the third process according to the invention can be conducted at standard pressure, elevated pressure or reduced pressure. Preferably, the process according to the invention can be conducted at standard pressure.

Elevated pressure may be a pressure from 1.1 bar to 100 bar, preferably of 1.5 bar to 50 bar, more preferably of 2 bar to 20 bar and very preferably of 2 to 10 bar.

Reduced pressure may be a pressure of 1 mbar to 1000 mbar, preferably 1 mbar to 500 mbar, more preferably 1 mbar to 250 mbar, very preferably 5 mbar to 100 mbar.

The second step of the third process according to the invention can be conducted between 20° C. and 150° C., preferably between 40° C. and 100° C., more preferably between 45° C. and 80° C.

The reaction in the second step of the third process according to the invention can be effected without solvent or in a solvent, for example methanol, ethanol, propanol, butanol, cyclohexanol, N,N-dimethylformamide, dimethyl sulphoxide, pentane, hexane, cyclohexane, heptane, octane, decane, toluene, xylene, acetone, acetonitrile, carbon tetrachloride, chloroform, dichloromethane, 1,2-dichloromethane, tetrachloroethylene, diethyl ether, methyl tert-butyl ether, methyl ethyl ketone, tetrahydrofuran, dioxane, pyridine or ethyl acetate. The solvent may preferably be ethanol.

The reaction in the second step of the third process according to the invention can be conducted without organic solvent. The solvent may be water.

The reaction product from the second step of the third process according to the invention can be filtered, and the filtercake can be washed with an organic solvent. Preferably, an alcohol can be used for washing, more preferably ethanol, or an alkane, more preferably hexane.

The solvent in the second step of the third process according to the invention can subsequently be removed, preferably distilled off.

The reaction product in the second step of the third process according to the invention can be dried after filtration and removal of solvent. The drying can be effected at temperatures of 20° C.-100° C., preferably of 25° C.-50° C. The drying can be effected at a reduced pressure of 1-500 mbar.

The urea-containing silane of the formula I, obtainable in the second step by the third process according to the invention,

can be obtained in a yield of greater than 50%, preferably greater than 60%, very preferably greater than 70%.

In a preferred embodiment of the third process according to the invention, the isocyanatosilane of the formula VII can be metered at −78 to −50° C. into the amine of the formula VIII in ethanol, then the reaction mixture can be heated to 50° C., sodium polysulphide of the formula V can be added in portions, then the mixture can be refluxed, preferably at 78° C., cooled after the reaction has ended and filtered, and the ethanol solvent can be removed under reduced pressure.

The product prepared by the third process according to the invention may have a residual content of urea-containing halosilane of the formula VI of less than 25 mol %, preferably less than 10 mol %, more preferably less than 5 mol %, very preferably less than 3 mol %.

The relative molar percentages of the urea-containing halosilanes of the formula VI in the product prepared by the third process according to the invention are determined in the ¹H NMR by integration of the hydrogen atoms in the —CH₂CH ₂—Cl group of the urea-containing halosilanes of the formula VI against the hydrogen atoms in the Si—CH ₂— group of the urea-containing silane of the formula I.

For the substance of the formula VI (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—Cl, for example, the integral of the hydrogen atoms of the —CH₂CH ₂—Cl group (δ=3.17 ppm) is used for the determination of the relative contents.

The product prepared by the third process according to the invention may have a residual content of isocyanatosilane of the formula VII of less than 10 mol %, preferably less than 5 mol %, more preferably less than 1 mol %, very preferably less than 0.1 mol %.

The relative molar percentages of the isocyanatosilanes of the formula VII in the product within a range of >1 mol %, prepared by the third process according to the invention, are determined in the ¹³C NMR by integration of the carbon atoms in the —NCO group of the isocyanatosilanes of the formula VII against the carbon atoms in the Si—CH₂— group of the urea-containing silane of the formula I.

For the substance of the formula VII (EtO)₃Si—CH₂—CH₂—CH₂—NCO, for example, the integral of the carbon atoms of the —NCO group (δ=122.22 ppm) is used for the determination of the relative contents within a range of >1 mol %.

The relative molar percentages of the isocyanatosilanes of the formula VII in the product within a range of <1 mol %, prepared by the third process according to the invention, are determined by quantitative FT-IR spectroscopy known to those skilled in the art. The method is calibrated by using calibration solutions of suitable concentration (for example in C₂Cl₄). For the measurement, about 1 g sample is weighed into a 25 ml rollneck bottle, and 25 g of C₂Cl₄ are added. The sample is agitated on an agitator for 1-2 hours. Thereafter, the lower liquid phase is metered cautiously into a 20 mm IR cuvette and analysed by FT-IR spectroscopy (4000-1200 cm⁻¹, resolution 2 cm⁻¹). Under the same conditions, a spectrum of the solvent is recorded for subtraction.

For the substance of the formula VII (EtO)₃Si—CH₂—CH₂—CH₂—NCO, for example, the wavelength of the valence vibration of the —NCO group at 2270 cm⁻¹ is used for the determination of the relative contents within a range of <1 mol %.

The product prepared by the third process according to the invention may have a residual content of amine of the formula VIII of less than 25 mol %, preferably less than 10 mol %, more preferably less than 5 mol %, very preferably less than 3 mol %.

The relative molar percentages of the amines of the formula VIII in the product prepared by the third process according to the invention are determined in the ¹³C NMR by integration of the carbon atoms in the —CH₂—NH₂ group of the amines of the formula VIII against the carbon atoms in the Si—CH₂— group of the urea-containing silane of the formula I.

For the substance of the formula VIII H₂N—CH₂—CH₂—Cl, for example, the integral of the carbon atoms of the H₂N-CH₂—CH₂—Cl group (δ=39.47 ppm) or of the H₂N—CH₂—CH₂—Cl group (δ=37.95 ppm) is used for the determination of the relative contents.

The amine of the formula VIII can be prepared, prior to the reaction with the isocyanatosilane of the formula VII, from the hydrochloride salt of the amine of the formula IX

by addition of a base, preferably NaOEt. The base can be added until a pH between 7 and 14 is established.

In a preferred embodiment, the third process for preparing urea-containing silanes of the formula I

where x, R and R1 are each as defined above may be characterized in that the hydrochloride salt of the amine of the formula IX

is dissolved in ethanol and reacted with a base, then the isocyanatosilane of the formula VII

is added, then sodium polysulphide of the formula V

Na₂S_(x)  (V)

is added, the mixture is filtered and the solvent is removed.

The product prepared by the third process according to the invention may have a residual content of hydrochloride salt of the amine of the formula IX of less than 25 mol %, preferably less than 10 mol %, more preferably less than 5 mol %, very preferably less than 3 mol %.

The relative molar percentages of the hydrochloride salt of the amine of the formula IX in the product prepared by the third process according to the invention are determined in the ¹³C NMR by integration of the carbon atoms in the —CH₂—NH₂.HCl group of the hydrochloride salt of the amine of the formula IX against the carbon atoms in the Si—CH₂— group of the urea-containing silane of the formula I.

For the substance of the formula IX HCl.H₂N—CH₂—CH₂—Cl, for example, the integral of the carbon atoms of the HCl.H₂N-CH₂—CH₂—Cl group (δ=41.25 ppm) or of the HCl.H₂N—CH₂—CH₂—Cl group (δ=40.79 ppm) is used for the determination of the relative contents.

Urea-containing silanes of the formula I prepared by the processes according to the invention can be characterized by a ¹H, ¹³C or ²⁹Si NMR method known to those skilled in the art.

The soluble fraction of the urea-containing silanes of the formula I in the products obtained by the processes according to the invention in DMSO-d⁶ or CDCl₃ is determined by adding an internal standard, for example triphenylphosphine oxide (TPPO), in DMSO-d6 or in CDCl₃, and a ¹H NMR method known to those skilled in the art.

The urea-containing silanes of the formula I can be used as adhesion promoters between inorganic materials, for example glass beads, glass flakes, glass surfaces, glass fibres, or oxidic fillers, preferably silicas such as precipitated silicas and fumed silicas, and organic polymers, for example thermosets, thermoplastics or elastomers, or as crosslinking agents and surface modifiers for oxidic surfaces.

The urea-containing silanes of the formula I may be used as coupling reagents in filled rubber mixtures, examples being tyre treads, industrial rubber articles or footwear soles.

Advantages of the inventive urea-containing silanes of the formula I are improved processing characteristics and rolling resistance in rubber mixtures.

EXAMPLES Comparative Example 1 Preparation of [(EtO)₃Si—(CH₂)₃—NH—C(═O)—NH—(CH₂)₂—S-]₂ in water

An N2-purged 1 l jacketed four-neck flask with precision glass stirrer, reflux condenser, internal thermometer and dropping funnel is initially charged with cystamine dihydrochloride (108.39 g, 0.47 mol, 1.00 eq) which was dissolved in demineralized water (382 ml). By means of a dropping funnel, 50% KOH solution (92.31 g, 0.82 mol, 1.75 eq) is metered in at 15-23° C. and the mixture is stirred for 30 min. Then 3-isocyanatopropyltriethoxysilane (221.05 g, 0.85 mol, 1.8 eq) is metered in at such a rate that an internal temperature of 30° C. is not exceeded. Thereafter, the mixture is stirred at 24° C. for one hour. The white suspension is filtered under pressure, rinsed with three portions of demineralized water (340 ml in total) and dried with dry N₂ for 2 h. The filtercake is dried in an N₂ stream in a rotary evaporator at 35° C. and 166 mbar for 7 h, at 35° C. and 150 mbar for 10 h and at 35° C. and 100 mbar for 9 h. The [(EtO)₃Si—(CH₂)₃—NH—C(═O)—NH—(CH₂)₂—S-]₂ product is a fine white powder (246.38 g, 90.7% of theory);

¹H NMR (δ_(ppm), 500 MHz, DMSO-d6): 0.52 (4H, t), 1.14 (18H, t), 1.42 (4H, m), 2.74 (4H, m), 2.96 (4H, m), 3.29 (4H, m), 3.74 (12H, q), 6.05 (4H, m);

¹³C NMR (δ_(ppm), 125 MHz, DMSO-d6): 7.3 (2C), 18.2 (6C), 23.5 (2C), 38.5 (2C), 39.6 (2C), 42.0 (2C), 57.7 (6C) 157.9 (2C).

²⁹Si NMR (δ_(ppm), 100 MHz, DMSO-d6): −45.3 (100% silane);

Soluble fractions in d6-DMSO using TPPO internal standard: 86.0%;

Water content (DIN 51777): 0.7%;

Initial melting point: 97° C.;

Residual isocyanate content: 0.08%

Example 1 Preparation of (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ from (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₂—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ and Elemental Sulphur (Analogously to First Process According to the Invention)

A dry, N2-purged three-neck flask with stirrer, reflux condenser and internal thermometer is initially charged with (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₂—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ (5.00 g, 7.7 mmol, 1.00 eq) and elemental sulphur (0.50 g, 15.5 mol, 2.00 eq), and the mixture is heated to 140° C. and stirred for 2 h. After cooling, the (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ product (4.16 g, 75.8% of theory) is obtained as a viscous red oil which solidifies later to give an orange solid.

¹H NMR (δ_(ppm), 500 MHz, CDCl₃): 0.61 (4H, t), 1.20 (18H, t), 1.57 (4H, m), 2.68 (4H.2S content, t), 2.93 (4H.S4 content, t), 2.97 (4H.Sx content, t), 3.13 (4H, m), 3.53 (4H, m), 3.78 (12H, q), 5.1-6.9 (4H, br);

S4 content in the product mixture (includes Sx content about <5%, S4 content superposed): 85.5 mol %, S2 content in the product mixture: 14.5 mol %;

¹³C NMR (δ_(ppm), 125 MHz, CDCl₃): 7.7 (2C), 18.3 (6C), 23.7 (2C), 38.8 (2C), 40.7 (2C), 42.9 (2C), 58.4 (6C), 158.6 (2C).

²⁹Si NMR (δ_(ppm), 100 MHz, CDCl₃): −42.9 (5% Si—OH), −45.5 (85% silane), −53.4 (10% M structures);

Soluble fractions in CDCl₃ using TPPO internal standard: 84.2%;

Initial melting point: 170-207° C.;

Example 2 Preparation of (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ from (EtO)₃Si—CH₂CH₂CH₂—NH₂, OCN—CH₂CH₂—Cl and Na₂S₄ (Analogously to Second Process According to the Invention)

In a first reaction step, 3-aminopropyltriethoxysilane (73.05 g, 0.33 mol, 1.00 eq) is initially charged in pentane (2.5 l) in a 4 l three-neck flask with precision glass stirrer, internal thermometer, dropping funnel and reflux condenser, and cooled to −78° C. 2-Chloroethyl isocyanate (34.82 g, 0.33 mol, 1.00 eq) is added dropwise at −78 to −70° C. within 4.5 h and then the mixture is warmed to room temperature. The white suspension is filtered, washed with pentane and dried with N₂ overnight. The (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—Cl intermediate (113.41 g, quantitative) is a white, flaky powder.

In a second reaction step, (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—Cl (105.62 g, 0.32 mol, 2.00 eq) is initially charged in ethanol (200 ml) in a 500 ml three-neck flask with stirrer, reflux condenser and internal thermometer. Sodium polysulphide (Na₂S₄, 26.59 g, 0.16 mol, 1.00 eq) which has been crushed with a mortar and pestle is added and the mixture is heated to reflux. After a reaction time of 4.5 h, the mixture is cooled to room temperature and the suspension is filtered. The filtrate is freed of the solvent on a rotary evaporator and dried under reduced pressure. The (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ product (72.35 g, 64.2% of theory) is obtained as an orange solid.

¹H NMR (δ_(ppm), 500 MHz, d6-tol): 0.72 (4H, t), 1.21 (18H, t), 1.75 (4H, m), 2.65 (4H.2S content, t), 2.89 (4H.S4 content, t), 3.25-3.35 (4H, 2S/4S, m), 3.40-3.60 (4H, 2S/4S, m), 3.81 (12H, q), 5.5-6.0 (4H, br);

S4 content in the product mixture (includes Sx content about <5%): 69.0 mol %

S2 content in the product mixture: 31.0 mol %;

Initial melting point: 78-95° C.

Example 3 Preparation of (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ from (EtO)₃Si—CH₂CH₂CH₂—NH₂, OCN—CH₂CH₂—Cl and Na₂S₄ (Analogously to Second Process According to the Invention)

In a first reaction step, 3-aminopropyltriethoxysilane (154.95 g, 0.70 mol, 1.00 eq) is initially charged in ethanol (3.0 l) in a 4 l three-neck flask with precision glass stirrer, internal thermometer, dropping funnel and reflux condenser, and cooled to −78° C. 2-Chloroethyl isocyanate (73.86 g, 0.70 mol, 1.00 eq) is added dropwise at −78 to −60° C. within 1 h, in the course of which a voluminous salt precipitates out. Then the mixture is heated to 50° C., sodium polysulphide (Na₂S₄, 57.62 g, 0.35 mol, 1.00 eq) which has been crushed with a mortar and pestle is added in portions and the mixture is heated to reflux. After a reaction time of 4.5 h, the mixture is cooled to room temperature and the suspension is filtered. The filtrate is freed of the solvent on a rotary evaporator and dried under reduced pressure. The (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ product (155.05 g, 63.1% of theory) is obtained as an orange solid.

¹H NMR (δ_(ppm), 500 MHz, d6-tol): 0.7 (4H, t), 1.21 (18H, t), 1.75 (4H, m), 2.65 (4H.2S content, t), 2.89 (4H.S4 content, t), 3.25-3.35 (4H, 2S/4S, m), 3.40-3.60 (4H, 2S/4S, m), 3.81 (12H, q), 5.5-6.0 (4H, br);

S4 content in the product mixture (includes Sx content about <5%): 64.0 mol %

S2 content in the product mixture: 36.0 mol %;

Initial melting point: 78-91° C.

Example 4 Preparation of (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ from (EtO)₃Si—CH₂CH₂CH₂—NH₂, OCN—CH₂CH₂—Cl and Na₂S₄ (Analogously to Third Process According to the Invention)

In a first reaction step, 2-chloroethylamine hydrochloride (73.86 g, 0.70 mol, 1.00 eq) is initially charged in ethanol (3.0 l) in a 4 l three-neck flask with precision glass stirrer, internal thermometer, dropping funnel and reflux condenser, and cooled to −78° C., and sodium ethoxide (226.83 g, 0.70 mol, 1.00 eq, 21% in ethanol) is added. 3-Isocyanatopropyl(triethoxysilane) (173.15 g, 0.70 mol, 1.00 eq) is then added dropwise at −78 to −70° C. within 3 h and then the mixture is heated to 50° C. Dry sodium polysulphide (Na₂S₄, 57.62 g, 0.35 mol, 0.50 eq) is added in five portions and the mixture is heated to reflux. After a reaction time of 4 h, the mixture is cooled to room temperature and the suspension is filtered. The filtrate is freed of the solvent on a rotary evaporator and dried under reduced pressure. The (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃ product (214.5 g, quant.) is obtained as a red oil.

S4 content in the product mixture (includes Sx content about <5%, S4 content superposed): 85.5 mol %, S2 content in the product mixture: 14.5 mol %.

Example 5

The formulation used for the rubber mixtures is specified in Table 1 below. In this table, the unit phr means parts by weight based on 100 parts by weight of the raw rubber used. The inventive silane and the comparative silane are used in 3 different concentrations, in the isomolar ratio in each case.

TABLE 1 Amount Amount Amount Amount [phr] [phr] [phr] [phr] Amount Amount Ref. Ref. Ref. Rubber [phr] [phr] rubber rubber rubber mixture Rubber Rubber mixture I mixture mixture I, mixture mixture cont. II III cont. II, III, Comp. cont. cont. Inv. cont. cont. Ex. 1 Comp. Ex. 1 Comp. Ex. 1 Ex. 3 Inv. Ex. 3 Inv. Ex. 3 1st stage NR TSR^(a) 10 10 10 10 10 10 BR^(b) 18 18 18 18 18 18 SSBR^(c) 72 72 72 72 72 72 Silica^(d) 95 95 95 95 95 95 ZnO 2.5 2.5 2.5 2.5 2.5 2.5 Stearic acid 2.5 2.5 2.5 2.5 2.5 2.5 TDAE oil 50 50 50 50 50 50 Antiozonant 2 2 2 2 2 2 wax 6PPD^(e) 2 2 2 2 2 2 Comp. Ex. 1 7.9 9.3 10.7 Example 3 — — — 8.4 9.9 11.4 2nd stage Batch Stage 2 DPG^(f) 2 2 2 2 2 2 CBS^(g) 2 2 2 2 2 2 Sulphur 2 2 2 2 2 2 Substances used: ^(a)NR TSR: SIR 20 SED, from Aneka Bumi Pratama (TSR = Technically Specified Rubber; SIR = Standard Indonesian Rubber) ^(b)BR: polybutadiene, Europrene Neocis BR 40, from Polimeri ^(c)SSBR: Sprintan ® SLR-4601, from Styron ^(d)silica: ULTRASIL ® VN3 GR, from Evonik Industries AG ^(e)6PPD: N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine ^(f)DPG: diphenylguanidine ^(g)CBS: N-cyclohexyl-2-benzothiazolesulphenamide

The mixture was produced under customary conditions in two stages in a laboratory kneader for production of rubber mixtures (volume 300 millilitres to 3 litres), by first mixing, in the first mixing stage (base mixing stage), all the constituents apart from the vulcanization system (sulphur and vulcanization-influencing substances) at 145 to 165° C., target temperatures of 152 to 157° C., for 200 to 600 seconds. Addition of the vulcanization system in the second stage (ready-mix stage) produces the finished mixture, with mixing at 90 to 120° C. for 180 to 300 seconds.

The general process for producing rubber mixtures and vulcanizates thereof is described in “Rubber Technology Handbook”, W. Hofmann, Hanser Verlag 1994.

The rubber testing is effected by the test methods specified in Table 2.

TABLE 2 Physical testing Standard/conditions Ring tensile test, 23° C. DIN 53504 Stress values (MPa) Reinforcement index Rebound resilience at 23° C. and 70° C. DIN 53512 (%) Dynamic/mechanical analysis at 55° C. ISO 4664-1 Maximum loss factor tan δ (max)

The mixtures are used to produce test specimens by vulcanization under pressure at 160° C. after t₉₅ (measured on a moving die rheometer to ISO 6502/ASTM D5289-12). Table 3 reports the rubber data.

TABLE 3 Substance Ref. Ref. Rubber Ref. rubber rubber mixture Rubber Rubber rubber mixture mixture I, mixture mixture mixture I II III cont. II, III, cont. cont. cont. Inv. cont. cont. Vulcanizate results: Comp. Ex. 1 Comp. Ex. 1 Comp. Ex. 1 Ex. 3 Inv. Ex. 3 Inv. Ex. 3 100% stress value 2.1 2.3 2.5 2.7 2.8 3.0 [mPa] 300% stress value 6.7 7.2 7.9 8.7 9.6 10.4 [mPa] Reinforcement 5.1 5.3 5.3 5.6 6.2 6.5 index: 300%/50% stress value [—] Rebound resilience 25.9 25.8 26.4 26.1 27.0 27.4 23° C. [%] Rebound resilience 43.1 44.0 45.1 46.1 49.9 50.5 70° C. [%] Rebound resilience 17.2 18.1 18.8 20.0 23.0 23.1 70° C. − rebound resilience 23° C. Dynamic/mechanical 0.201 0.199 0.199 0.186 0.180 0.174 analysis at 55° C. tan δ max. at 55° C.

Rubber mixtures I-Ill containing the inventive urea-containing silane from Example 3 show improved reinforcement characteristics (higher moduli and better reinforcement indices), improved rolling resistance indicators (rebound resilience at 70° C. and tan δ max.). The key conflict between rolling resistance and wet grip is resolved better with the inventive urea-containing silane (rebound resilience 70° C.-rebound resilience 23° C., rebound resilience at 70° C. and tan δ max.) compared to the respective comparative example with isomolar usage. 

What is claimed is:
 1. A urea-containing silane of the formula I

where each R¹ is independently selected from the group consisting of a C1-C10 alkoxy group, a C2-C10 cyclic dialkoxy group, a phenoxy group, a C4-C10 cycloalkoxy group, a C6-C18 aryl group, a C1-C10 alkyl group, a C2-C20 alkenyl group, a C7-C20 aralkyl group or a halogen, and each R is a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C₁-C₃₀ hydrocarbyl group and x is an integer from 3 to
 8. 2. The urea-containing silane according to claim 1, wherein the urea-containing silane is ((EtO)₃Si—CH₂—NH—CO—NH—CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂, ((EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂—NH—CO—NH—CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂, ((MeO)₃Si—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂ or ((MeO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—S_(x/2))₂.
 3. The urea-containing silane according to claim 1, wherein the urea-containing silane is (EtO)₃Si—CH₂CH₂CH₂—NH—CO—NH—CH₂CH₂—S₄—CH₂CH₂—NH—CO—NH—CH₂CH₂CH₂—Si(OEt)₃.
 4. A process for preparing the urea-containing silane of claim 1, comprising reacting a urea-containing disulphide silane of formula II

with sulphur, where R and R¹ are each as defined in claim
 1. 5. The process of claim 4, wherein the reaction is conducted under a protective gas atmosphere.
 6. The process of claim 4, wherein the reaction is conducted under standard pressure.
 7. The process of claim 4, wherein the reaction is conducted without solvent.
 8. A process for preparing the urea-containing silane of claim 1, wherein, in a first step, an aminosilane of the formula III

is reacted with an isocyanate of formula IV

where R and R¹ are each as defined in claim 1 and Hal is F, Cl, Br or I, and, in a second step, the product from the first step is reacted with a sodium polysulphide of formula (V) Na₂S_(x)  (V) where x is as defined in claim
 1. 9. The process of claim 8, wherein the first step is conducted under a protective gas atmosphere.
 10. The process of claim 8, wherein the second step is conducted under a protective gas atmosphere.
 11. The process of claim 8, wherein ethanol is used as a solvent in the first step.
 12. The process of claim 8, wherein ethanol is used as a solvent in the second step.
 13. A process for preparing the urea-containing silane of claim 1, wherein, in a first step, an isocyanatosilane of formula VII

is reacted with an amine of formula VIII

where R and R¹ are each as defined in claim 1 and Hal is F, Cl, Br or I, and, in a second step, the product from the first step is reacted with a sodium polysulphide of the formula V Na₂S_(x)  (V) where x is as defined in claim
 1. 14. The process of claim 13, wherein the amine of formula VIII, prior to reaction with the isocyanatosilane of the formula VII, is prepared by adding a base to a hydrochloride salt of a diamine of formula IX Cl⁻⁺H₃N—R—S—S—R—NH₃ ⁺Cl⁻  IX.
 15. The process of claim 14, wherein the base is NaOEt.
 16. The process of claim 13, wherein ethanol is used as a solvent in the first step.
 17. The process of claim 13, wherein ethanol is used as a solvent in the second step. 